Abstract [en]

The interface between land surfaces and the atmosphere is a key area in climate research, where lack of basic knowledge prevents us from reducing the considerable uncertainties about predicted changes. Boreal forests play an important, but not well known, role in the global hydrological and biogeochemical cycles. NOPEX (a NOrthern hemisphere climate Processes land surface EXperiment) is devoted to the study of land surface-atmosphere interaction in a northern European forest-dominated landscape. The main NOPEX region represents the southern edge of the boreal zone. It consists of a highly heterogeneous landscape, with forests, mires, agricultural land and lakes. A second study site, in northern Finland, representing the northern edge of the boreal zone, will be introduced into NOPEX in connection with its coming winter-time field activities. Field activities, dominating the initial phase of NOPEX, are conceived to strike a balance between the need to cover multi-annual observations and the resources required to carry out measurements covering all relevant spatial scales. The long-term data collection activities, the Continuous Climate Monitoring (CCM), form the backbone of the field programme. A suite of Concentrated Field Efforts (CFEs) covering periods of summer, spring and winter brings together scientists from more then 20 countries during month-long campaigns. CFEs have been carried out in May-June 1994 and April-July 1995. A third, winter-time CFE is planned for 1998-99. The System for Information in NOPEX (SINOP) is the database which forms a backbone for modelling and analysis work, dominating the second stage of NOPEX. A series of PhD courses are run in parallell to the research activities. Analysis and modelling are done in four interacting areas, including local-scale processes, meso-scale surface-atmosphere coupling and remote sensing techniques. The fourth area, regionalization methods, aims at bringing the previous three together in order to provide improved parameterization schemes for exchange of energy, momentum, water and CO2 between land and atmosphere in hydrological and meteorological models from the meso to the global scale.